The surgical removal of impacted mandibular third molar remains to be one of the most commonly performed procedures in Oral and Maxillofacial Surgery. Despite being routine, it is often associated with a series of post-operative sequelae such as pain, edema and reduction in mouth opening, which collectively aggravates patient comfort and quality of life in the immediate recovery period (1). These inflammatory responses are typically a result of tissue trauma and subsequent release of inflammatory mediators like prostaglandins and cytokines (2).

Corticosteroids have long been employed as a pharmacological intervention to mitigate post-operative inflammation. Amongst them, dexamethasone is widely favored due to its long half-life, high anti-inflammatory potency and relatively low mineralocorticoid activity (3). It effectively suppresses the early vascular phase of inflammation and reduces capillary permeability, thereby minimizing tissue edema and pain (4).

Various routes of dexamethasone administration have been explored in the context of third molar surgery, including oral, intravenous (IV), intramuscular (IM) and submucosal (SM) routes. While IV and IM routes provide systemic action, they may be associated with slightly more discomfort during administration and also require more clinical skills for administration. In contrast, the SM route offers localized delivery with potentially fewer systemic effects, making it a practical alternative in outpatient dental settings (5).

However, limited data exist directly comparing the efficacy of these routes in terms of their impact on post-operative outcomes following mandibular third molar surgery. This study was undertaken to compare the effectiveness of dexamethasone administered via submucosal, intravenous and intramuscular routes in minimizing post-operative discomfort following third molar surgery.

A total of 60 healthy individuals aged 18-35 years who required surgical removal of a single impacted mandibular third molar were chosen for the study. Sample size was based on previous studies comparing post-operative outcomes across corticosteroid administration routes, with an 80% power and 5% significance level. Participants were randomly assigned into three groups (n = 20 per group) using computer-generated randomization.

Inclusion and Exclusion Criteria

Inclusion criteria:

• Patients with mesioangular or vertical impacted mandibular third molars classified as Class I, Level B (Pell and Gregory classification)
• ASA Class I patients (American Society of Anesthesiologists)
• No prior corticosteroid or NSAID use within one week before surgery

Exclusion criteria:

• Known allergy to dexamethasone
• Presence of acute infection at the surgical site
• Pregnant or lactating women
• Immunocompromised individuals or those with systemic illness

Intervention Protocol

Facial measurements and maximum interincisal distance were noted before the procedure. All surgical procedures were carried out under local anesthesia using 2% lignocaine with 1:80,000 epinephrine by a single experienced surgeon for standardization and to minimize variability and possibility of bias associated with different surgeons' techniques and skills. Before incision, each group received 8 milligrams of dexamethasone injection immediately after administration of local anesthesia by the following route:

• Group I (SM): Submucosal injection into the buccal vestibule adjacent to the surgical site
• Group II (IV): Intravenous injection in the antecubital vein
• Group III (IM): Intramuscular injection into the deltoid muscle

Surgical Procedure

A standard envelope flap was raised and bone around the tooth was carefully removed using a straight handpiece and copious saline irrigation. Tooth sectioning was performed where required, and tooth was elevated out followed by bone filing, curettage. After thorough betadine and saline irrigation, wound was closed using 3-0 silk sutures.

Evaluation
Patients were recalled for follow-up on post-operative days 1, 3 and 7.

Following perameters were assessed on each follow-up.

• Pain: Measured using a 10-point Visual Analogue Scale (VAS)
• Edema: Assessed using linear facial measurements between fixed anatomical landmarks (tragus-pogonion, tragus-oral commissure and lateral canthus-gonion)
• Trismus: Evaluated by measuring the maximum interincisal distance using a calibrated Vernier caliper

Statistical Analysis

All data were recorded and analysed using SPSS software (version 26.0). Descriptive statistics were computed and intergroup comparisons were done using one-way ANOVA, followed by post-hoc Tukey’s test for pairwise analysis. A p-value less than 0.05 was considered statistically significant

A total of 60 patients completed the study with 20 patients in each group (Submucosal, Intravenous and Intramuscular). The demographic distribution was compared across the three groups with no statistically significant difference in age or gender (p > 0.05).

Pain Assessment (VAS Score)

Pain intensity was recorded using the Visual Analogue Scale on post-operative days 1, 3 and 7. Group I (Submucosal) consistently showed lower mean pain scores as compared to Groups II (IV) and III (IM). Differences were statistically significant (p < 0.05) (Table 1).

Table 1: Comparison of Mean Pain Scores (VAS) Across Groups

Facial Edema

Facial edema was measured using standardized linear measurements. On day 1, Group I showed a mean increase of 4.5 mm in facial dimension, which was significantly less than Group II (6.2 mm) and Group III (7.0 mm). The same trend was noted on day 3. While on day 7, edema had reduced substantially in all groups (Table 2).

Table 2: Comparison of Mean Edema (mm) Across Groups

Mouth Opening (Maximum Interincisal Distance)

Trismus was assessed by measuring the reduction in maximum interincisal opening. On day 1, Group I exhibited the least reduction in mouth opening (8.3 mm) as compared to Group II (10.6 mm) and Group III (12.1 mm). This trend continued on day 3, with Group I showing the least reduction (5.1 mm), followed by Group II (6.4 mm) and Group III (7.2 mm), and the differences were statistically significant (p = 0.03). Recovery was observed in all groups on day 7 (Table 3).

Table 3: Comparison of Reduction in Mouth Opening (mm) Across Groups

The above findings illustrates that submucosal administration of dexamethasone results in significantly better outcomes in reducing post-operative pain, edema and trismus, especially in the immediate post-operative phase (Tables 1-3).

The surgical removal of impacted mandibular third molars is commonly associated with a series of post-operative events such as pain, edema and trismus, which significantly impacts patient recovery and quality of life. These inflammatory responses are predominantly due to tissue trauma that triggers the release of various chemical mediators, including prostaglandins and bradykinins, leading to increased vascular permeability and edema (1,2). The use of corticosteroids, particularly dexamethasone, has been widely advocated to control this inflammatory cascade owing to its potent anti-inflammatory and immunosuppressive effects (3,4).

In the present study, submucosal (SM) administration of dexamethasone revealed superior outcomes in controlling post-operative discomfort as compared to intravenous (IV) and intramuscular (IM) routes. This finding aligns with previous studies suggesting that localized administration of corticosteroids provide more targeted anti-inflammatory action at the surgical site, with fewer systemic effects (5,6). The submucosal route, in particular, has been reported to allow sustained local drug availability due to slow tissue absorption, enhancing therapeutic efficacy in the early post-operative period (7).

Pain assessment indicated that patients receiving SM dexamethasone experienced significantly lower VAS scores, especially on post-operative days 1 and 3. This observation supports the work of Majid and Mahmood, who found that localized dexamethasone reduced pain more effectively in the first 48 hours post-procedure (8). In contrast, although IV dexamethasone provides rapid systemic circulation, its efficacy may wane off quicker due to its faster clearance from the bloodstream (9).

Edema, a major concern post-surgery, was also least pronounced in the SM group, corroborating the findings of Grossi et al., who reported reduced facial edema with submucosal steroid delivery (10). The ability of dexamethasone to stabilize lysosomal membranes and reduce capillary permeability directly impacts edema and when administered closer to the inflammatory site, its anti-edematous effects are more pronounced (11).

Regarding trismus, the reduction in maximum interincisal opening was lowest in the SM group, indicating better preservation of masticatory function. Similar findings have been noted in the studies by Bhargava et al. and Rakhshan et al., who reported lower degree of trismus in patients receiving localized corticosteroid therapy (12,13). This effect can be attributed to the decreased inflammatory infiltration in the masticatory muscles and periosteum.

The IM route, although effective, showed delayed onset of action and greater post-injection discomfort, which might explain its relatively mediocre outcomes in this study. Moreover, the IM route does not allow direct action at the surgical site, potentially limiting its effectiveness (14).

From a practical standpoint, the SM route offers several advantages, including ease of administration, minimal invasiveness and the ability to deliver the drug during the same operative session under local anesthesia without patient discomfort. It eliminates the need for additional venipuncture or intramuscular injection, improving patient compliance and clinical efficiency (15).

Submucosal administration of dexamethasone proved to be the most effective route in minimizing post-operative pain, edema and trismus following mandibular third molar surgery. It offers a safe, simple and efficient method with superior clinical outcomes as compared to intravenous and intramuscular routes.

1. Latt MM, Kiattavorncharoen S, Boonsiriseth K, Pairuchvej V, Wongsirichat N. The efficacy of dexamethasone injection on postoperative pain in lower third molar surgery. J Dent Anesth Pain Med. 2016;16(2):95-102.
2. Boonsiriseth K, Latt MM, Kiattavorncharoen S, Pairuchvej V, Wongsirichat N. Dexamethasone injection into the pterygomandibular space in lower third molar surgery. Int J Oral Maxillofac Surg. 2017;46(7):899-904.
3. Wanithanont P, Chaiyasamut T, Vongsavan K, Bhattarai BP, Pairuchvej V, Kiattavorncharoen S, et al. Comparative efficiency of the preoperative pterygomandibular space injection of two doses of dexamethasone in mandibular third molar surgery. J Dent Anesth Pain Med. 2021;21(1):29-39.
4. Moranon P, Chaiyasamut T, Sakdajeyont W, Vorakulpipat C, Klongnoi B, Kiattavornchareon S, et al. Dexamethasone injection into pterygomandibular space versus sublingual space on post-operative sequelae of lower third molar intervention. J Clin Med Res. 2019;11(7):501-508.
5. Sitthisongkhram K, Niyomtham N, Chaiyasamut T, Pairuchvej V, Kc K, Wongsirichat N. Effectiveness of dexamethasone injection in the pterygomandibular space before and after lower third molar surgery. J Dent Anesth Pain Med. 2020;20(5):313-323.
6. Poorna P, Shetty P, Kalyani V, Shetty S, Upadya M, Mithra P. A comparative evaluation of the effect of addition of 8 mg dexamethasone to 2% lignocaine with adrenaline in mandibular third molar surgery: a split-mouth randomised double-blind study. Front Oral Health. 2024;5:1349832.
7. Lim D, Ngeow WC. A comparative study on the efficacy of submucosal injection of dexamethasone versus methylprednisolone in reducing postoperative sequelae after third molar surgery. J Oral Maxillofac Surg. 2017;75(11):2278-2286.
8. Arora SS, Phull T, Kumar I, Kumar A, Kumar N, Singh H. A comparative study of the effect of two dosages of submucosal injection of dexamethasone on postoperative discomfort after third molar surgery: a prospective randomized study. Oral Maxillofac Surg. 2018;22(2):225-230.
9. Klongnoi B, Kaewpradub P, Boonsiriseth K, Wongsirichat N. Effect of single-dose preoperative intramuscular dexamethasone injection on lower impacted third molar surgery. Int J Oral Maxillofac Surg. 2012;41(3):376-379.
10. Gozali P, Boonsiriseth K, Kiattavornchareon S, Khanijou M, Wongsirichat N. Decreased post-operative pain using a sublingual injection of dexamethasone (8 mg) in lower third molar surgery. J Dent Anesth Pain Med. 2017;17(1):47-53.
11. Ruthvik S, Krishnan M, George M, Kumar SP, Lakshmanan S. Efficacy of dexamethasone diluted saline irrigant on postoperative sequelae in patients undergoing lower third molar surgery: a prospective clinical study. Cureus. 2023;15(9):e45436.
12. Deo SP. Single-dose of submucosal injection of dexamethasone affects the postoperative quality of life after third molar surgery. J Maxillofac Oral Surg. 2016;15(3):367-375.
13. Chugh A, Singh S, Mittal Y, Chugh V. Submucosal injection of dexamethasone and methylprednisolone for the control of postoperative sequelae after third molar surgery: randomized controlled trial. Int J Oral Maxillofac Surg. 2018;47(2):228-233.
14. Deo SP. Effect of submucosal injection of dexamethasone on post-operative sequelae of third molar surgery. JNMA J Nepal Med Assoc. 2011;51(182):72-78.
15. Sreesha S, Ummar M, Sooraj S, Aslam S, Roshni A, Jabir K. Postoperative pain, edema and trismus following third molar surgery - A comparative study between submucosal and intravenous dexamethasone. J Family Med Prim Care. 2020;9(5):2454-2459